Is there a removable insert to keep the back rigid ? Either that or a water bladder pocket.
I like a good mystery. What happens when you loosen the strap as far as it will go?You might have to drop a line to customer services.
A strap there normally adjusts how high the pack sits, or how low depending on your point of view, so it can be adjusted for different users back length.
The strap is to tension the internal support panel. When the strap is loosened it makes it easier to remove the internal frame. Although we do not recommend this.
Really? Never heard of anything like that, wonder if they're right? Their webpage says it has an adjustable back system so my money is still on the strap that does that